Making sampling easy:

I use Medhat's two jar windshield wiper fluid method. 

But I would add: an insect vac. You can easily collect the right amount of bees in seconds.  

I got mine from Bioquip for around $100. It has a cord which plugs into the "cigarette lighter jack".

It appears they don't sell that one anymore; they have a cordless one for a lot more $$. 

https://bioquipinc.com/catalog/collecting-equipment-supplies/aspirators-vacs/heavy-duty-hand-held-dc-vacaspirator/

some of the other insect vacs might work

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